Tension control apparatus and method for aero-mechanical conveyor

ABSTRACT

An improved tension control apparatus for use in an aero-mechanical conveyor for moving bulk materials, the conveyor including upper and lower housings, head and tail pulley assemblies mounted on respective shafts positioned within the upper and lower housings, respectively, spaced-apart inflow and outflow conveyor tubes interconnecting the upper and lower housings, and an endless rope assembly disposed within the conveyor tubes and around the head and tail pulleys. The improvement includes a bracket cooperating with the inflow and outflow conveyor tubes. A guide sleeve is carried by the bracket for receiving a push rod. The push rod extends along the length of the conveyor tubes from the guide sleeve to the upper housing and includes an upper end engaging the head pulley assembly and a lower end extending through the guide sleeve. A tensioning assembly engages the lower end of the push rod and is carried by the bracket for urging the push rod against the head pulley assembly, thereby urging the head pulley assembly away from the tail pulley assembly and maintaining the rope assembly in a tensioned condition.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

This application claims priority of European Patent Application No. 01303 023.4, filed Mar. 29, 2001. This invention relates to a tensioncontrol apparatus and tensioning method for an aero-mechanical conveyor.Aero-mechanical conveyors are often used to convey powders and otherparticulate matter by entraining the particulate matter in a movingairstream. Such conveyors typically include an endless wire ropeassembly upon which dividers are fastened and used for carryingparticulate matter. The rope assembly is typically carried on drive anddriven pulleys enclosed within infeed, corner and dischargesemi-circular housings in various configurations. The housings areinterconnected by two tubes through which the rope assembly travels asit moves around the drive and driven pulleys. As the conveyor operates,forces are exerted on the rope assembly that can cause the rope assemblyto stretch. Such forces are created by normal wear on the conveyor, theweight of the material being conveyed along the rope assembly, andsimilar other factors, and can cause the rope assembly to stretch to thepoint that the amount of tension initially exerted on the rope assemblyis inadequate.

While prior art manual tension adjusting mechanisms exist for moving thehead and tail pulley assemblies relative to each other to maintain thecorrect amount of tension on the rope assembly, such mechanisms areoften inadequate. For example, some traditional prior art tensionadjusting mechanisms rely on clamps which fasten the semi-circularhousings to the tubes. Tension on the rope assembly is adjusted byloosening the bolts that hold the clamps in place and sliding one orboth of the housings inwardly or outwardly relative to the tubes.Another prior art method of adjusting the tension on the rope assemblyinvolves moving the drive or driven pulley together with the housing.Regardless of which prior art method is employed, adjusting the tensionby moving the housings relative to the conveyor tubes is a manualoperation. In addition, the discharge end of the equipment is frequentlyinaccessible, making access to the tube-joining clamps challenging. Theclamps nonetheless have to be slackened and re-tightened. Furthermore,once the tension has been adjusted, there is no guarantee that the tubesand the connecting spigots leading to the housings will be properlyaligned, which makes jamming almost inevitable.

The invention of the present application overcomes the problems inherentto the prior art described above by providing a tension controlapparatus for use on an aero-mechanical conveyor that adjusts tension bymoving the housings and pulley assemblies automatically and withoutrequiring any significant manual intervention. The tension controlapparatus of the present invention uses compression springs to maintaina pre-selected amount of tension on the rope assembly. One embodiment ofthe invention also uses cams to ensure that the drive centers cannot bepulled together by an increase in tension on the rope assembly due tothe exertion of drive or other forces. The present invention canaccommodate a total rope stretch of 16 mm before the tension controlapparatus must be reset, and includes a novel reset lever which providesa visual indication of when such a reset is needed. The invention of thepresent application not only provides a simple procedure for accuratelyresetting the tension on the rope assembly, but also permits a user toquickly and easily reset the tension to an amount equivalent to thatoriginally set at commissioning, thereby ensuring that an adequateamount of tension is maintained on the rope assembly at all times.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide anaero-mechanical conveyor having components which facilitate easyhandling and installation, and provide low maintenance operation.

It is another object of the present invention to provide an aeromechanical conveyor that includes a tension control apparatus thatprovides a visual and repeatable indication of the tensioning forceapplied to the rope assembly on the conveyor.

It is another object of the present invention to provide anaero-mechanical conveyor that includes sliding seals having anegligible, constant frictional drag, thereby permitting the force beingapplied to the rope assembly by the tensioning arrangement to be easilydetermined.

It is another object of the invention to provide an aero mechanicalconveyor that includes a tension control apparatus capable of continuoususe 365 days each year.

It is another object of the present invention to provide anaero-mechanical conveyor that includes a tension control apparatus whichcan be used in vertical, angled or horizontal aero-mechanical conveyorsystems.

These and other objects of the present invention are achieved in thepreferred embodiments disclosed below by providing an improved tensioncontrol apparatus for use in an aero-mechanical conveyor for moving bulkmaterials. The conveyor includes upper and lower housings, and head andtail pulley assemblies mounted on respective shafts positioned withinthe upper and lower housings, respectively. Spaced-apart inflow andoutflow conveyor tubes interconnect the upper and lower housings. Anendless rope assembly is disposed within the conveyor tubes and aroundthe head and tail pulley assemblies. The improvement includes a bracketthat cooperates with the inflow and outflow conveyor tubes. A guidesleeve is carried by the bracket for receiving a push rod. The push rodextends along the length of the conveyor tubes from the guide sleeve tothe upper housing and includes an upper end engaging the head pulleyassembly and a lower end extending through the guide sleeve. Atensioning assembly engages the lower end of the push rod and is carriedby the bracket for urging the push rod against the head pulley assembly,thereby urging the head pulley assembly away from the tail pulleyassembly and maintaining the rope assembly in a tensioned condition.

According to one preferred embodiment of the invention, the bracket iscarried on the inflow and outflow conveyor tubes.

According to another preferred embodiment of the invention, thetensioning assembly includes a spring carried thereon urging thetensioning assembly against the push rod for maintaining the ropeassembly in the tensioned condition.

According to yet another preferred embodiment of the invention, thetensioning assembly further includes at least one upper plate connectedto the bracket and guide sleeve. A lower plate engages the lower end ofthe push rod. At least one bolt interconnects the upper and lower platesand includes a first end extending through the lower plate; and a secondend extending through the upper plate. The second end has acomplementary nut releasably attached thereto for being selectivelytightened or loosened for urging the upper and lower plates toward oraway from each other, thereby respectively increasing or decreasing thetensioned condition of the rope.

According to yet another preferred embodiment of the invention, thespring is concentrically positioned along the length of the bolt andcaptured between the upper plate and the nut, thereby permitting thespring to contract or expand in response to a respective increase ordecrease in the tensioned condition of the rope.

According to yet another preferred embodiment of the invention, thetensioning apparatus includes a cam carried on the push rod. The cam isin abutting engagement with a cam follower carried on the push rod andis positioned for rotation against the cam follower caused by upwardmovement of the cam follower in response to a decrease in the tensionedcondition of the rope assembly, thereby maintaining the rope assembly ina preselected tensioned condition.

According to yet another preferred embodiment of the invention, theimprovement further includes first and second dust cap sealsinterconnecting the inflow and outflow conveyor tubes with the upperhousing for reducing emissions of particulate matter from the conveyor.

According to yet another preferred embodiment of the invention, one ofthe first and second dust cap seals is positioned on a respective one ofthe inflow and outflow conveyor tubes for permitting sliding, sealingmovement of the inflow and outflow conveyor tubes relative to the upperhousing, thereby correcting radial misalignment of the tubes relative tothe upper housing and reducing friction on the rope assembly.

A method for maintaining a predetermined tension on an endless ropeassembly of an aero-mechanical conveyor is provided in which the ropeassembly is disposed around head and tail pulleys mounted on respectiveshafts positioned within upper and lower housings and positioned withinspaced-apart inflow and outflow conveyor tubes interconnecting the upperand lower housings. The method include the steps of providing a bracketcooperating with the inflow and outflow conveyor tubes, and providing aguide sleeve carried by the bracket for receiving a push rod. The pushrod extends along the length of the conveyor tubes from the guide.sleeve to the upper housing and includes an upper end engaging the headpulley assembly and a lower end extending through the guide sleeve. Themethod also includes the step of providing a tensioning assembly whichengages the lower end of the push rod. The tensioning assembly iscarried by the bracket for urging the push rod against the head pulleyassembly, thereby moving the head pulley assembly away from the tailpulley assembly and maintaining the rope assembly in the tensionedcondition. The head and tail pulley assemblies are positioned at apreselected fixed center distance relative to one another, therebyplacing the rope assembly in the predetermined tensioned condition. Thetensioning assembly is adjusted within a range of adjustment tocompensate for a decrease in the tensioned condition of the ropeassembly, thereby adjusting the center distance and the tensionedcondition as the tension control apparatus operates.

A method for maintaining a predetermined tension on an endless ropeassembly of an aero-mechanical conveyor according to yet anotherpreferred embodiment of the invention is provided in which thetensioning apparatus includes a cam carried on the push rod and inabutting engagement with a cam follower carried on the push rod. The camis positioned for rotation against the cam follower caused by upwardmovement of the cam follower in response to a decrease in the tensionedcondition of the rope assembly, thereby maintaining the rope assembly ina preselected tensioned condition.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the objects of the invention have been set forth above. Otherobjects and advantages of the invention will appear as the inventionproceeds when taken in conjunction with the following drawings, inwhich:

FIG. 1 is a cut-away side elevation of a tension control apparatusaccording to an embodiment of the present invention shown in use on anaero-mechanical conveyor;

FIG. 2 is a fragmentary side elevation of the tension control apparatusshown in FIG. 1;

FIG. 3 is a top plan elevation of the tension control apparatus shown inFIG. 1 and removed from the aero-mechanical conveyor;

FIG. 4 is a fragmentary side elevation of the tension control apparatusshown in FIG. 1, viewed 90 degrees from the view in FIG. 1;

FIG. 5 is an environmental side elevation of a tension control apparatusaccording to another embodiment of the invention in use on anaero-mechanical conveyor;

FIG. 6 is a fragmentary side elevation of the tension control apparatusshown in FIG. 5;

FIG. 7 is a top plan elevation of the tension control apparatus shown inFIG. 6 and removed from the aero mechanical conveyor;

FIG. 8 is an enlarged side elevation of a push rod assembly included inthe tension control apparatus shown in FIGS. 5, 6 and 7;

FIG. 9 is a fragmentary side elevation of the tension control apparatusshown in FIG. 6, viewed 90 degrees from the view in FIG. 6; and

FIG. 10 is a fragmentary enlarged side elevation of an eccentric camassembly included in the tension control apparatus shown in FIGS. 5, 6,7 and 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE

Referring now specifically to the drawings, an aero-mechanical conveyoraccording to the present invention is illustrated in FIG. 1 and showngenerally at reference numeral 10. The conveyor 10 includes an upperhousing 12 and an infeed housing 14, which are interconnected by inflowand outflow conveyor tubes 16. and 18, respectively. The upper housing12 includes a top portion 20 which is removably attached to a bottomportion 22 along first and second angle flanges 24 and 26, respectively.The top portion 20 may be removed for permitting access to the interiorof the upper housing 12 for inspection and maintenance, and defines anoutlet opening 28 through which particulate matter exits the conveyor10. The upper housing 12 may optionally include a discharge chute likethe discharge chute 160 shown in FIG. 5.

The infeed housing 14 includes an inlet hopper 30 in which particulatematter “P” is stored. Head and tail pulley assemblies 32 and 34 aremounted on respective lower and upper shafts 36 and 38, which arepositioned in the infeed housing 14 and upper housing 12, respectively.A continuous rope assembly 40 upon which multiple identical disks 42 arecarried is disposed around the head and tail pulley assemblies 32 and34, and extends through the respective inflow and outflow conveyor tubes16 and 18. A drive mechanism 44 is positioned adjacent the infeedhousing 14 and is operatively connected to the lower shaft 36. The drivemechanism 44 drives the lower shaft 36, causing the head pulley assembly32 to rotate. This in turn drives the tail pulley assembly 34, andcauses the rope assembly 40 to travel in the direction “D” shown. As therope assembly travels, the disks 42 to carry particulate matter “P” fromthe inlet hopper 30 through the inflow conveyor tube 16, and into theupper housing 12, where the particulate matter exits the conveyor 10through the outlet opening 28. Although the drive mechanism 44 is shownin FIG. 1 operatively connected to the lower shaft 36, the drivemechanism 44 may alternatively be operatively connected to the uppershaft 38 (Not shown).

As discussed in detail with reference to FIGS. 2 through 4 below, theconveyor 10 also includes a tensioning assembly 46 which maintains apreselected amount of tension on the rope. assembly 40. While thetensioning assembly 46 is shown in FIG. 1 in use on a verticalaero-mechanical conveyor, the tensioning assembly 46 may alternativelybe used on an angled or horizontal conveyor, or on a conveyor havinginterconnected vertical and horizontal configurations.

Referring again to FIG. 1, inflow conveyor tube 16 includes. an inlettube 48 having a lower end 50 which is connected to infeed housing 14.The inlet tube 48 also includes a flared upper end 52. A first uppertubular portion 54 interconnects inlet tube 48 with the bottom portion22 of upper housing 12. Tubular portion 54 has an upper end 56 connectedto the bottom portion 22 and a lower end 58 upon which a lead-in flare60 is positioned. Tubular portion 54 may alternatively be used withoutthe lead-in flare 60 positioned on the lower end 58. Lower end 58 isreceived within and fluidly communicates with the flared upper end 52 ofinlet tube 48. Outflow conveyor tube 18 similarly includes an outlettube 62 having a lower end 64 and a flared upper end 66. A second uppertubular portion 68 interconnects the outlet tube 62 with the bottomportion 22 of upper housing 12. Second upper tubular portion 68 has anupper end 70 which is connect to the bottom portion 22, and a lower end72 which is received within and fluidly communicates with the flaredupper end 66 of outlet tube 62.

Inflow and outflow conveyor tubes 16 and 18 also include first andsecond flexible dust cap seals 74 and 76, respectively. First dust capseal 74 covers and encircles flared upper end 52 and lower end 58.Second dust cap seal 74 covers and encircles flared upper end 66 andlower end 72. Dust cap seals 74 and 76 provide a sliding seal betweenthe upper and lower ends 52 and 58, and upper and lower ends 62 and 72,respectively. Each dust cap seal 74 and 76 is a proprietary item and ispreferably formed from silicone material approved to FDA 177.2600. Dustcap seals 74 and 76 not only reduce emissions of particulate matter fromthe conveyor 10, but also allow respective inflow and outflow conveyortubes 16 and 18 to move relative to the upper housing 12. Permittingmovement of the tubes 16 and 18 in this manner corrects radialmisalignment of the tubes 16 and 18 relative to the upper housing 12,and reduces friction and subsequent premature wear on the rope assembly40. While the dust cap seals 74 and 76 are shown in FIG. 1 in use withflared upper ends 52 and 66, respectively, the natural elasticity of theseals 74 and 76 makes them equally suited for use on pipes having solidor rolled ends.

Referring now to FIG. 2, the manual tensioning assembly 46 is mounted ona tube clamp 80 which is mounted on and extends between inlet tube 48and outlet tube 62. As is shown in FIG. 3, tube clamp 80 is formed fromfirst and second clamp segments 81A and 81B, respectively, which areconnected together by multiple identical bolts 82, upon whichcomplementary nuts 84 are releasably attached. Connected segments 81Aand 81B define two openings 84 and 85 through which inlet tube 48 andoutlet tube 62, respectively, extend.

Referring again to FIG. 2, a first guide sleeve 86 is mounted on tubeclamp 80 and is positioned between inlet tube 48 and outlet tube 62. Asecond tube clamp 87 is mounted on and extends between the inlet tube 48and outlet tube 62. Second tube clamp 87 is positioned between the firsttube clamp 80 and flared upper ends 52 and 66, respectively. A secondguide sleeve 88 is positioned between inlet tube 48 and outlet tube 62and is in vertical alignment with first guide sleeve 86. An elongatepush rod 90 extends through first and second guide sleeves 86 and 88,respectively. Push rod 90 has a lower end 92 that extends through firstguide sleeve 86 and an upper end 94 which extends through second guidesleeve 88. Upper end 94 engages a base plate 100 upon which head pulleyassembly 34 is mounted. Although the upper end 94 of push rod 90 isshown in FIGS. 1 and 2 engaging the base plate 100, the upper end 94 mayalternatively be connected to the upper housing 12. The push rod 90 mayalso alternatively be connected to the infeed housing 14 for moving theinfeed housing 14 relative to the upper housing 12. In an aeromechanicalconveyor employing corner housings, one or more push rods 90 mayalternatively be connected to one or more corner housings for movingthose corner housings relative to other housings included on theconveyor.

Referring now to FIG. 4, a sprocket 102 carries the rope assembly 40 andis mounted on upper shaft 38. Upper shaft 38 extends through one side ofthe upper housing 12 perpendicularly to the plane upon which ropeassembly 40 travels. The upper shaft 38 is carried by and extendsthrough bearing housings 106.

Referring again to FIG. 2, the tensioning assembly 46 also includes anupper plate 114 and a pressure plate 116. Upper plate 114 is connectedto the tube clamp 80 and guide sleeve 86, and pressure plate 116 engagesthe lower end 92 of the push rod 90. Upper plate 114 and pressure plate116 are interconnected by two identical tensioning bolts 118, each ofwhich has a first end 120 that extends through the pressure plate 116and a second end 122 that extends through the upper plate 114. Arespective one of two complementary nuts 124 is releasably attached tothe second end 122 of each bolt 118.

The tensioning assembly 46 also includes two springs 126, each of whichis positioned concentrically along a respective one of the bolts 118.Each spring 126 is preferably a compression spring, and is capturedbetween the upper plate 114 and a respective one of the nuts 124. Whilethe tensioning assembly 46 is show in use with compression springs,stacks of Belleville washers, gas struts, pneumatic cylinders, or anelectrical actuator may alternatively be employed to adjust the tension.

The tensioning assembly 46 is used to maintain a preselected amount oftension on the rope assembly 40 by adjusting the center distance “C_(D)”between the lower and upper shafts 36 and 38. See FIG. 1. To set thedesired center distance “C_(D)”, each nut 124 is tightened or loosenedon its respective bolt 118, which causes the spring positioned on thebolt 118 to contract or expand, respectively. Expansion of the springs126 creates an increase in the force of the springs 126 on the upperplate 114, and causes the pressure plate 116 to move towards the upperplate 114, which in turn causes upward movement of the push rod 90.Upward movement of the push rod 90 moves the upper housing 12 and thetail pulley assembly 34 away from the head pulley assembly 32, whichincreases both the center distance “C_(D)” and the tension on the ropeassembly 40. In contrast, contraction of the springs 126 causes adecrease in the force of the springs 126 on the upper plate 114, whichpulls the pressure plate 116 away from the upper plate 114. The push rod90 moves downwardly in response, which moves the upper housing 12 andthe tail pulley assembly 34 away from the head pulley assembly 32,thereby decreasing not only the center distance “C_(D)”, but also thetension on the rope assembly 40.

Once the center distance “C_(D)” is set and the conveyor 10 begins tooperate, the increased load on the rope assembly 40 created by theweight of the particulate matter carried on the disks 42 causes the ropeassembly 40 to stretch, thereby decreasing the tension on the ropeassembly 40.

As is shown in FIG. 1, the tensioning assembly 46 also includes alocking bolt 128, which may be tightened to secure the first guidesleeve 86 to the lower end 92 of the push rod 90. This prevents theguide sleeve 86 from rattling while the conveyor operates. When theguide sleeve 86 is secured to the lower end 92 in this manner, thecenter distance “C_(D)” will not change during service in response todecreases in tension on the rope assembly 40. A user operating theconveyor 10 must instead slacken the locking bolt 128 at regularmaintenance intervals to inspect the springs 126 to determine whetherthey have moved. If so, the user must reset the springs 126 to theiroriginal position.

If the locking bolt 128 is not used, the springs 126 will automaticallyexpand to compensate for the decrease in tension that occurs as the ropeassembly 40 stretches. As discussed above, this expansion causes thepressure plate 116 to move upwardly toward the upper plate 114, which inturn causes the push rod 90 to move upwardly, thereby increasing thetension on the rope assembly 40 to compensate for the loss of tensioncreated as the rope assembly 40 stretches.

Although the tensioning assembly 46 effectively compensates fordecreases in tension on the rope assembly 40 as the rope assembly 40stretches, like other conventional “resilient” tensioning devices, thetensioning assembly 46 does not respond effectively to sudden changes indynamic tension as the conveyor 10 operates. Specifically, duringoperation of a near-vertical conveyor such as the conveyor 10, thedynamic tension on the rope assembly 40 may be 50% higher than thestatic tension. The springs 126 respond to this difference by expandingor contracting accordingly, which moves the center distance “C_(D)” awayfrom the optimum. Any instantaneous increase. in load caused, forexample, by an obstruction due to snagging or large particle size, cancause an abrupt increase in tension on the rope assembly 40 and promptan unexpected change in the center distance “C_(D)”. Such a suddenchange can cause the rope assembly 40 to slacken behind the obstructionenough to get out of pitch and cause a complete jam within the conveyor10.

Referring now to FIG. 5, an alternative embodiment of an aero-mechanicalconveyor according to the present invention is illustrated and showngenerally at reference numeral 130. Designed to overcome the problemsassociated with sudden increases in dynamic tension described above, theconveyor 130 does not rely upon the tensioning assembly 46, but insteadutilizes a non-resilient tensioning assembly 140. The conveyor 130 alsoincludes an upper housing 142 and an infeed housing 144, which areinterconnected by inflow and outflow conveyor tubes 146 and 148,respectively. The upper housing 142 includes a top portion 150 which isremovably attached to a bottom portion 152 along first and second angleflanges 154 and 156, respectively. The top portion 150 may be removedfor permitting access to the interior of the upper housing 132 forinspection and maintenance, and defines an outlet opening 158. Adischarge chute 160 is removably attached to the top portion 150adjacent the outlet opening 158 along third and fourth angle flanges 162and 164, respectively. Discharge chute 160 directs particulate matterpassing through the outlet opening 158 away from the conveyor 130.Discharge chute 160 may optionally be removed from the conveyor 130.

The infeed housing 144 includes an inlet hopper 166 in which particulatematter “P” is stored. Head and tail pulley assemblies 168 and 170 aremounted on respective lower and upper shafts 172 and 174, which arepositioned in the infeed housing 144 and upper housing 142,respectively. A continuous rope assembly 180 upon which multipleidentical disks 182 are carried is disposed around the head and tailpulley assemblies 168 and 170, and extends through the respective inflowand outflow conveyor tubes 146 and 148. A drive mechanism 184 ispositioned adjacent the infeed housing 144 and is operatively connectedto the lower shaft 172. The drive mechanism 184 drives the lower shaft172, causing the head pulley assembly 168 to rotate. This in turn drivesthe tail pulley assembly 170, and causes the rope assembly 180 to travelin the direction “D” shown for permitting the disks 182 to carryparticulate matter from the inlet hopper 166 through the inflow conveyortube 146, into the upper housing 142, and out of the conveyor 130through the discharge chute 160. The drive mechanism 184 mayalternatively be operatively connected to the upper shaft 174 (Notshown).

As is shown in FIG. 5, inflow conveyor tube 146 includes an inlet tube186 having a lower end 188 which is received within the inlet hopper166, and a flared upper end 190. A first upper tubular portion 192interconnects inlet tube 186 with the bottom portion 152 of upperhousing 142. Tubular portion 192 has an upper end 194 connected to thebottom portion 152 and a lower end 196 upon which a lead-in flare 198 ispositioned. Tubular portion 192 may alternatively be utilized withoutthe lead-in flare 198 on the lower end 196. Lower end 196 is receivedwithin and is in fluid communication with the flared upper end 190 ofinlet tube 186. Outflow conveyor tube 148 similarly includes an outlettube 200 having a lower end 202 and a flared upper end 204. A secondupper tubular portion 206 interconnects the outlet tube 200 with thebottom portion 152 of upper housing 142. Second upper tubular portion206 has an upper end 208 which is connected to the bottom portion 152,and a lower end 210 which is received within and fluidly communicateswith the flared upper end 204 of outlet tube 200.

Inflow and outflow conveyor tubes 146 and 148 also include first andsecond flexible dust cap seals 212 and 214, respectively. First dust capseal 212 covers and encircles flared upper end 190 and lower end 196.Second dust cap seal 214 covers and encircles flared upper end 204 andlower end 210. Dust cap seals 212 and 214 are formed from the samematerials and perform the same functions as the dust cap seals 74 and 76described above and shown in FIG. 1.

Referring now to FIG. 6, the tensioning assembly 140 is mounted on atube clamp 216. Tube clamp 216 is mounted on and extends between inlettube 186 and outlet tube 200. As is shown in FIG. 7, tube clamp 216includes first and second clamp segments 218A and 218B, respectively,which cooperate with each other to define two openings 220A and 220Bthrough which inlet tube 186 and outlet tube 200, respectively, extend.See FIG. 5. Segments 218A and 218B are connected together by multipleidentical bolts 222, upon which complementary nuts 224 are releasablyattached.

Referring again to FIG. 5, the conveyor 10 also includes second andthird tube clamps 226 and 228, respectively. Each tube clamp 226 and 228includes the same components and is formed in the same manner as tubeclamp 216. The second tube clamp 226 is mounted on and extends betweeninlet tube 186 and outlet tube 200. The second tube clamp 226 is alsopositioned adjacent flared upper ends 190 and 204, and has a secondguide sleeve 230 mounted thereon. Second guide sleeve 230 is preferablyformed from a short length of rectangular or round tube. The third tubeclamp 228 is mounted on and extends between inlet tube 186 and outlettube 200 intermediate the first and second tube clamps 216 and 226,respectively. While the third tube clamp 228 shown in FIG. 5 does notinclude a guide sleeve, such a sleeve may be installed thereon, ifdesired. The guide sleeve 230 shown on the second tube clamp 226 islikewise an optional component. Additional tube clamps may be installedwhich are preferably positioned along the inlet tube 186 and outlet tube200 eight feet apart from one another. Furthermore, the guide sleeve 230or any other equivalent guide sleeve mounted on the conveyor 10 mayalternatively include a locking bolt identical to the locking bolt 128shown in FIG. 2. While such a bolt would normally be left slack orremoved altogether to allow the tensioning assembly 140 to operate, thebolt would have a role in setting up the assembly 140 for operation.

Referring again to FIG. 6, the tensioning assembly 140 includes an upperplate 232 and a pressure plate 234. Upper plate 232 is connected to thetube clamp 216 and a threaded guide tube 236, which is likewiseconnected to the tube clamp 216. Guide tube 236 is preferably formedfrom a short length of 1.5″ NB tube having an outside diameter of 48.3″and a threaded top end 238. The top end 238 carries a pressure collar240 and locking nut 241. Upper plate 232 and pressure plate 234 areinterconnected by two identical tensioning bolts 242, each of which hasa first end 243 that extends through a respective one of two identicalholes 243A defined in the pressure plate 234 and a second end 244 thatextends through the upper plate 232. A respective one of twocomplementary nuts 246 is releasably attached to the second end 244 ofeach bolt 242. The tensioning assembly 140 also includes two springs248, each of which is positioned concentrically along a respective oneof the bolts 242. Each spring 248 is preferably a compression spring,and is captured between the upper plate 232 and a respective one of thenuts 246. While the tensioning assembly 140 illustrated in FIGS. 5, 6,and 8 is shown in use with compression springs, stacks of Bellevillewashers, gas struts, pneumatic cylinders, or an electrical actuator mayalternatively be employed for adjusting the tension.

As is shown in FIG. 6, passing through the guide tube 236 is a firstpush rod 250 having a top end 252, and a bottom end 254 which isconnected to the pressure plate 234 by a bolt 256. As is shown in FIG.8, a complementary hole 258 is defined in the bottom end 252 of the pushrod 250 for receiving the bolt 254 therein. A bore 278 is defined by andextends through the top end 256 of the first push rod 250. A flat plate260 is welded to the top end 252, and includes an upper surface 262 towhich a rectangular pad 264 is attached. As is shown in FIG. 6, therectangular pad 264 is received within a complementary mouth 268 formedon the lower end 270 of a support post 272. As is shown in FIG. 5, thesupport post 272 extends between the inflow and outflow conveyor tubes146 and 148, respectively, and has an upper end 274 that extends throughthe guide sleeve 230. The upper end 274 engages a base plate 276 uponwhich the head pulley assembly 170 is mounted. The head pulley assembly170 is formed from the same components and is constructed in the samemanner as the head pulley assembly 34. Although the upper end 274 ofpush rod 250 is shown in FIG. 5 engaging the base plate 276, the upperend 274 may alternatively be connected directly to the upper housing142. The push rod 250 may also alternatively be connected to the infeedhousing 143 for moving the infeed housing 143 relative to the upperhousing 142. In an aeromechanical conveyor employing corner housings,one or more push rods 250 may alternatively be connected to one or morecorner housings for moving those corner housings relative to otherhousings included on the conveyor.

Referring now to FIG. 9, a short spindle 280 is positioned in andextends through the hole 278. Spindle 280 has first and second ends 282and 284, respectively, to which respective first and second eccentriccams 286 and 288 are keyed. A torsion spring 290 is positionedconcentrically along the second end 284 of the spindle 280 between cam288 and a first cover plate 300. See also FIG. 10. A reset lever 302 ispositioned on the first end 284 of the spindle 280 adjacent a secondcover plate 303, which is in turn positioned adjacent cam 288. Each cam286 and 288 has a 4 mm eccentricity, which gives a rise of 8 mm which inturn corresponds to a total rope stretch of 16 mm. As discussed indetail with reference to FIG. 6 below, the reset lever 302 serves as avisual indicator of the extent to which tension on the rope assembly 180has occurred during operation of the conveyor 130. Once the ropeassembly 180 has stretched 16 mm, the tensioning assembly 140 must bereset. If the rope assembly 180 stretches more than 80mm, totalrepositioning of the rope assembly 180 relative to the head and tailpulley assemblies 168 and 170, respectively, is required. Although thetensioning assembly 140 is shown in use with eccentric cams, thetensioning assembly 140 may alternatively employ any suitable non-returndevice for adjusting tension.

The tensioning assembly 140 is used to maintain a preselected amount oftension on the rope assembly 180. The tube clamp 216 is locked to theinlet and outlet tubes 186 and 200, respectively, in a position wherethe clamp 216, and tubes 186 and 200 are reasonably secure relative toone another. Tension is then applied to the rope assembly 180 bytightening each nut 246 on its respective tensioning bolt 242, whichcauses the springs 248 positioned along the tensioning bolts 242 tocontract. As the springs 248 contract, the force of the springs 248 onthe upper plate 232 increases, which pulls the pressure plate 234 towardthe upper plate 232. The push rod 250 moves upwardly in response, whichin turn moves upper housing 142 and the tail pulley assembly 170 awayfrom the head pulley assembly 168, thereby causing a increase in tensionon the rope assembly 180.

Provided that the upper housing 142 is not experiencing excessivefriction due to misalignment of the lower end 196 of tubular portion 192relative to the flared upper end 190 of inlet tube 186, and misalignmentof the lower end 210 of tubular portion 206 relative to the flared upperend 190 of inlet tube 200 (use of the dust cap seals 212 and 214 shouldensure this), a known amount of tension may be applied to the ropeassembly 180 by measuring the extent to which the springs 248 arecompressed. Alternatively, tension may be applied using conventionalempirical methods, and the length of the springs 248 subsequentlymeasured for future reference.

Referring again to FIG. 6, after the correct amount of tension has beenapplied to the rope assembly 180, the reset lever 302 is rotated to a“set” position “P_(SET)”, against the action of the torsion spring 190.The pressure collar 240 is then screwed up until it contacts each of theeccentric cam 286 and 288 at its minimum radius position “R_(MIN)”. Asthe conveyor 130 operates, and the rope assembly 180 stretches, thesprings 248 will continue to maintain the preselected tension on therope assembly 180, and any upward movement of the push rod 250 willallow the cams 286 and 288 to rotate under the action of the torsionspring 290.

Because the cams 286 and 288 each have a low ramp angle, the cams 286and 288 are each self-locking. Therefore, any additional tension appliedto the rope assembly 180 caused by drive forces or unexpected snaggingwill not move the push rod 250 and allow the rope center to increase.However, any slack in the rope assembly 180 will be immediately taken upby the springs 248, and maintained by the action of the cams 286 and288. As the rope assembly 180 stretches, each cam 286 and 288 rotates,which in turn causes the reset levers 300 and 302 to rotate, therebyserving as a visual indicator of the extent to which tension on the ropeassembly 180 has decreased. Upon rotation of each cam 286 and 288through 180 degrees, the respective reset levers 300 and 302 willlikewise rotate 180 degrees to a “reset” position “PRESET”. Movement ofthe reset lever 302 to the “reset” position “PRESET” indicates that eachcam 286 and 288 is at its maximum radius “R_(MAX)”, and can no longercompensate for any additional stretch in the rope assembly 180, and thatthe springs 248 have expanded to such an extent that an inadequatetensioning force is probably being exerted on the rope assembly 180.

To reset the tensioning assembly 140 so that the pre-selected tensionoriginally applied to the rope assembly 180 is restored, each nut 246 istightened on its respective tensioning bolt 242, which removes the forcebeing exerted by the pressure collar 240 on the cams 286 and 288. Thelocking nut 241 is then slackened, and the reset lever 302 is then movedto the “set” position “P_(SET)” and held in place against the action ofthe torsion spring 290. The pressure collar 240 is then turned until itcontacts the cams and 288 again. Locking nut 241 and nuts 246 are thentightened, thereby restoring the correct tension on the rope assembly180 so that the conveyor 130 can resume operating.

In the embodiments described above, the tension control apparatus of thepresent invention is shown in use on a vertical aero mechanical conveyorwhich includes only head and tail pulley assemblies positioned withininfeed and upper housings, respectively. However, the tension controlapparatus of the present invention may be utilized in combination withan aeromechanical conveyor having conveyor tubes, additional pulleys andcorresponding housings interconnected in any suitable arrangement, andincluding any suitable entry and exit points through which theparticulate matter being conveyed may enter or exit the conveyor.

A tension control apparatus for use in an aero-mechanical conveyor isdescribed above. Various details of the invention may be changed withoutdeparting from its scope. Furthermore, the foregoing description of thepreferred embodiment of the invention and the best mode for practicingthe invention are provided for the purpose of illustration only and notfor the purpose of limitation—the invention being defined by the claims.

We claim:
 1. In a tension control apparatus for use in anaero-mechanical conveyor for moving bulk materials, the conveyorincluding upper and lower housings, head and tail pulley assembliesmounted on respective shafts positioned within the upper and lowerhousings, respectively, spaced-apart inflow and outflow conveyor tubesinterconnecting the upper and lower housings, and an endless ropeassembly disposed within the conveyor tubes and around the head and tailpulleys, the improvement comprising: (a) a bracket cooperating with theinflow and outflow conveyor tubes; (b) a guide sleeve carried by saidbracket for receiving a push rod, said push rod extending along thelength of the conveyor tubes from said guide sleeve to the upper housingand including an upper end engaging the head pulley assembly and a lowerend extending through the guide sleeve; and (c) a tensioning assemblyengaging the lower end of the push rod and carried by the bracket forurging the push rod against the head pulley assembly, thereby urging thehead pulley assembly away from the tail pulley assembly and maintainingthe rope assembly in a tensioned condition.
 2. In a tension controlassembly according to claim 1, wherein said bracket is carried on theinflow and outflow conveyor tubes.
 3. In a tension control apparatusaccording to claim 2, wherein said tensioning assembly includes a springcarried thereon urging the tensioning assembly against the push rod formaintaining the rope assembly in the tensioned condition.
 4. In atension control apparatus according to claim 3, wherein said tensioningassembly further comprises: (a) at least one upper plate connected tothe bracket and guide sleeve; (b) a lower plate engaging the lower endof the push rod; and (c) at least one bolt interconnecting the upper andlower plates and including a first end extending through said lowerplate; and (d) a second end extending through said upper plate andhaving a complementary nut releasably attached thereto for beingselectively tightened or loosened for urging the upper and lower platestoward or away from each other, thereby respectively increasing ordecreasing the tensioned condition of the rope.
 5. In a tension controlapparatus according to claim 4, wherein said spring is concentricallypositioned along the length of the bolt and captured between the upperplate and said nut, thereby permitting the spring to contract or expandin response to a respective increase or decrease in the tensionedcondition of the rope.
 6. In a tension control apparatus according toclaim 1, wherein said tensioning apparatus comprises a cam carried onsaid push rod and in abutting engagement with a cam follower carried onthe push rod, said cam positioned for rotation against said cam followercaused by upward movement of the cam follower in response to a decreasein the tensioned condition of the rope assembly, thereby maintaining therope assembly in a preselected tensioned condition.
 7. In a tensioncontrol apparatus according to claim 6, wherein said bracket is carriedon the inflow and outflow conveyor tubes.
 8. In a tension controlapparatus according to claim 7, wherein said tensioning assemblyincludes a spring carried thereon urging the tensioning assembly againstthe push rod for maintaining the rope assembly in the tensionedcondition.
 9. In a tension control apparatus according to claim 8,wherein said tensioning assembly further comprises: (a) at least oneupper plate connected to the bracket and guide sleeve; (b) a lower plateengaging the lower end of the push rod; and (c) at least one boltinterconnecting the upper and lower plates and including a first endextending through said. lower plate; and (d) a second end extendingthrough said upper plate and having a complementary nut releasablyattached thereto for being selectively tightened or loosened for urgingthe upper and lower plates toward or away from each other, therebyrespectively increasing or decreasing the tensioned condition of therope.
 10. In a tension control apparatus according to claim 9, whereinsaid spring is concentrically positioned along the length of the boltand captured between the upper plate and said nut, thereby permittingthe spring to contract or expand in response to a respective increase ordecrease in the tensioned condition of the rope.
 11. In a tensioncontrol apparatus for use in an aero-mechanical conveyor for moving bulkmaterials, the conveyor including upper and lower housings, head andtail pulley assemblies mounted on respective shafts positioned withinthe upper and lower housings, respectively, spaced-apart inflow andoutflow conveyor tubes interconnecting the upper and lower housings, andan endless rope assembly disposed within the conveyor tubes and aroundthe head and tail pulleys, the improvement comprising: (a) a bracketcooperating with the inflow and outflow conveyor tubes; (b) a guidesleeve carried by said bracket for receiving a push rod, said push rodextending along the length of the conveyor tubes from said guide sleeveto the upper housing and including an upper end engaging the head pulleyassembly and a lower end extending through the guide sleeve; and (c) atensioning assembly engaging the push rod and carried by the bracket forurging the push rod against the head pulley assembly, thereby urging thehead pulley assembly and the upper housing away from the tail pulleyassembly and maintaining the rope assembly in a tensioned condition. 12.In a tension control apparatus according to claim 11, wherein saidbracket is carried on the inflow and outflow conveyor tubes.
 13. In atension control apparatus according to claim 12, wherein said tensioningassembly includes a spring carried thereon urging the tensioningassembly against the push rod for maintaining the rope assembly in thetensioned condition.
 14. In a tension control apparatus according toclaim 13, wherein said tensioning assembly further comprises: (a) atleast one upper plate connected to the bracket and guide sleeve; (b) alower plate engaging the lower end of the push rod; and (c) at least onebolt interconnecting the upper and lower plates and including a firstend extending through said lower plate; and (d) a second end extendingthrough said upper plate and having a complementary nut releasablyattached thereto for being selectively tightened or loosened for urgingthe upper and lower plates toward or away from each other, therebyrespectively increasing or decreasing the tensioned condition of therope.
 15. In a tension control apparatus according to claim 12, whereinsaid spring is concentrically positioned along the length of the boltand captured between the upper plate and said nut, thereby permittingthe spring to contract or expand in response to a respective increase ordecrease in the tensioned condition of the rope.
 16. In a tensioncontrol apparatus according to claim 11, wherein said tensioningapparatus comprises a cam carried on said push rod in abuttingengagement with a cam follower carried on the push rod, said campositioned for rotation against said cam follower caused by upwardmovement of the cam follower in response to a decrease in the tensionedcondition of the rope assembly, thereby maintaining the rope assembly ina preselected tensioned condition.
 17. In a tension control apparatusaccording to claim 16, wherein said bracket is carried on the inflow andoutflow conveyor tubes.
 18. In a tension control apparatus according toclaim 17, wherein said tensioning assembly includes a spring carriedthereon urging the tensioning assembly against the push rod formaintaining the rope assembly in the tensioned condition.
 19. In atension control apparatus according to claim 18, wherein said tensioningassembly further comprises: (a) at least one upper plate connected tothe bracket and guide sleeve; (b) a lower plate engaging the lower endof the push rod; and (c) at least one bolt interconnecting said upperand lower plates and including a first end extending through said lowerplate; and (d) a second end extending through the upper plate and havinga complementary nut releasably attached thereto for being selectivelytightened or loosened for urging the upper and lower plates toward oraway from each other, thereby respectively increasing or decreasing thetensioned condition of the rope.
 20. In a tension control apparatusaccording to claim 19, wherein said spring is concentrically positionedalong the length of the bolt and captured between the upper plate andthe first nut, thereby permitting the spring to contract or expand inresponse to a respective increase or decrease in the tensioned conditionof the rope.
 21. In a method for maintaining a predetermined tension onan endless rope assembly of an aero-mechanical conveyor, the ropeassembly disposed around head and tail pulleys mounted on respectiveshafts positioned within upper and lower housings and positioned withinspaced-apart inflow and outflow conveyor tubes interconnecting the upperand lower housings, an improved method comprising the steps of: (a)providing a bracket cooperating with the inflow and outflow conveyortubes; (b) providing a guide sleeve carried by said bracket forreceiving a push rod, said push rod extending along the length of theconveyor tubes from said guide sleeve to the upper housing and includingan upper end engaging the head pulley assembly and a lower end extendingthrough the guide sleeve; c) providing a tensioning assembly engagingthe lower end of the push rod and carried by the bracket for urging thepush rod against the head pulley assembly, thereby moving the headpulley assembly away from the tail pulley assembly and maintaining therope assembly in the tensioned condition; and (d) positioning the headand tail pulley assemblies at a preselected fixed center distancerelative to one another, thereby placing the rope assembly in thepredetermined tensioned condition; and (e) adjusting the tensioningassembly within a range of adjustment to compensate for a decrease inthe tensioned condition of the rope assembly, thereby maintaining saidcenter distance and the tensioned condition as the tension controlapparatus operates.
 22. In a method for maintaining a predeterminedtension on an endless rope assembly of an aero-mechanical conveyoraccording to claim 21, wherein said tensioning apparatus comprises a camcarried on said push rod and in abutting engagement with a cam followercarried on the push rod, said cam positioned for rotation against saidcam follower caused by upward movement of the cam follower in responseto a decrease in the tensioned condition of the rope assembly, therebymaintaining the rope assembly in a preselected tensioned condition.